WHITE CROWS?

Most people think crows are black, and most are. A number of species in the genus Corvus,
however, have extensive white in their plumage.

One of my favorite species the White-necked
Raven, Corvus albicollis, of Africa, for example, has a
white collar (in addition to its way cool bill).

Some other species have extensive white on
other parts of their bodies as well.

Even those species that normally are black may
show patches of white on parts of their body, or may be
completely white.

American Crows, Corvus brachyrhynchos,
frequently show problems with pigment deposition. Approximately
1% of nestlings that I band in New York show some white in their
feathers, and four times that many have spots of white on their
toes, bill, or other part of the body. I find young like this
every year, and the occurrence is about what I would predict
based on seeing abnormal crows in large foraging flocks.

This nestling from my study in 1993 showed
rather extreme amounts of white relative to what I usually see.
(It was found dead on the Cornell Campus soon after fledging.)

Although I have had several young crows with
white in the wings in a single nest , I have not found white to
occur in the wings of young of the same adults over successive
years (but it could happen). I have a few families that have had
multiple broods of young with white spots on their toes, but the
numbers are small enough that I cannot distinguish them from
random occurrences at this point.

"Albinism" or some problem with
pigment production can be arrived at in a number of ways, many of
them quite distinct from each other. You can think of any
complex, enzyme and protein mediated process rather like starting
your car. Many things can go wrong, all of which result in you
not being able to start your car. You may not have the key, the
battery may be dead, the distributor cap may be missing, the car
may be out of gas, etc. Similarly, many factors can interfere
with the proper distribution of pigment in the feathers of birds,
resulting in white instead. The problems can be localized in time
and location (e.g., a damaged cell bed or a short term
poisoning), and result in white in restricted areas, such as the
crow illustrated above. If the problem in more basic (e.g., a
genetic mutation) or occurs earlier in development, the entire
bird can be affected.

Some crows can be completely white.

Here is an example of a nearly completely white
young American Crow photographed by Maxine and Jim
Harwood of Piedmont, Ohio, June 1998. It was a recently fledged youngster.
The Harwoods report seeing two white crows the next day, probably
this one and a sibling.

Notice on the one picture that the back is not
completely dark. Also, despite the red from the flash, the iris
was not pink, but was normally pigmented with blue-gray.

Another white crow
picture sent me recently by Burr Cornell of
Endicott, NY was of a bird seen in Vestal, New York on 25
October 1998. It shows black in the face and in the wings.